let hd:(a:number,b:number) => number;
hd = (x:number,y:number) => {
    return x + y;
}
console.log(hd(1,2));

// type定义对象类型
type UserType = {name:string;age:number;};
// type定义函数类型
type addUserFun = (user:UserType) => boolean;
let addUser1:addUserFun = (user:UserType) => {
    return true;
}
console.log(addUser1({name:"后盾人",age:18}));
